Conventional construction equipment such as hydraulic shovels and bulldozers with steel crawler belts being attached has the disadvantage of damaging asphalt road surfaces when traveling on a public road on the move between work sites, and therefore increasing number of vehicles are equipped with rubber crawler belts recently.
The rubber crawler belts are formed by a number of core wires and cores embedded in rubber in an endless shape, but it problems such as a crack and peeling of rubber occurs, it is difficult to repair them, which necessitates the replacement of the crawler belt to a new one, thereby causing the disadvantage of increasing user cost.
In order to overcome the foregoing disadvantage, elastic flat treads formed by iron crawler plates with elastic solids such as rubber being bonded thereto are used. Recently, an art is developed, in which a core is embedded into an elastic solid to construct an elastic flat tread, a plurality of which are disposed in a longitudinal direction of a crawler to thereby form an endless crawler belt.
As a prior art of an elastic flat tread, for example, Japanese Patent Application Laid-open No. 7-152305 is known, which will be explained with reference to FIG. 53 and FIG. 54. In an elastic flat tread 140, a planar core 120 is covered with an elastic solid 130 from the entire ground-contacting side toward core end portions 121 and 121 in a longitudinal direction of the core 120 on the side not in contact with the ground, and bonded thereto by vulcanization. The core 120 is fastened to a link 150 by bolts not illustrated. Numeral 132 is a bolt hole for insertion of the bolt.
However, in the above elastic flat tread 140, as shown in FIG. 55, elastic solid end portions 131 are locally bent to thereby cause the concentration of stress, when the elastic flat tread 140 runs on a protruding object such as a rock or stone A and a curb stone of a sidewalk not illustrated. As a result, the disadvantage of a crack P occurring in the elastic solid end portion 131 is caused. This is because the core 120 is designed to have high rigidity so as not to be deformed even if the vehicle weight W of construction equipment is exerted on the elastic flat tread 140 via a lower roller 145 and a link 150.
Meanwhile, even the elastic solid 130 with higher rigidity in nature has lower rigidity than that of the core 120. Consequently, when running on a protruding object such as a rock or stone A and a curb stone of a side walk, so long as the protruding object does not escape therefrom, distortion concentrates on the elastic solid 130 due to the difference in rigidity between the core 120 and the elastic solid 130, thereby causing the crack P in the elastic solid end portion 131 shown in FIG. 55.
Further, the head portions of bolts fastening the core 120 and the link 150 contact the elastic solid 130, thus causing the disadvantage that a crack and peeling occur at the bolt insertion holes 132.